Percutaneous endoscopic translaminar approach for herniated nucleus pulposus in the hidden zone of the lumbar spine

Introduction: Percutaneous endoscopic discectomy (PED) is the least invasive surgery for lumbar herniated nucleus pulposus (HNP). Most HNP can be removed through traditional PED approaches, but the challenging case is an HNP that has migrated into the hidden zone. We have established a percutaneous endoscopic translaminar approach (PETA) using the PED system to address such cases. Materials and Surgical Technique: Under fluoroscopy, an 8-mm skin incision is made 5 mm lateral to the midline. The PED cannula is placed on the lamina percutaneously. With a specially made high-speed drill with a diameter of 3.2 mm, a 4-mm bone hole is made. Through the bone hole, an HNP in the hidden zone can be detected. With a rongeur for PED, the HNP can be removed and then the decompressed nerve root is verified. We have treated nine cases of hidden-zone HNP. In all cases, the HNP was successfully removed, as confirmed by postoperative MRI. Clinical outcomes were acceptable: five showed excellent recovery and the remaining four were good. Discussion: We have introduced the PETA technique to safely access the hidden zone with the PED system. This approach is the least invasive technique for managing hidden-zone HNP.